Electrode for arc welding

ABSTRACT

An electrode for arc welding, comprising a core based on iron with alloying additives of chromium, nickel and titanium, and a coating consisting of fluorite, rutile concentrate, iron powder, chromium and mica. In addition to the above components, said coating also contains magnesite, ferrotitanium and ferroniobium that ensure high plasticity and resilience to the deposited metal, the latter thus being resistant to the formation of pores and hot cracks.

United States Patent 1191 Kakhovsky et a1. 0

[ ELECTRODE FOR ARC WELDING [76] Inventors: Nikolai Ivanovich Kakhovsky,

' pereulok Mechnikova, 3, kv. l;

Anatoly Nikolaevich Vakulenko, ul. Engelsa, 3, kv. 54; Leonid Stepanovich Zakharov, ul. Karla Marxa, 4, kv. 6; Vladimir Nikolaevich Lipodaev, pereulok Mechnikova, 4, kv. 27; Vladimir Grigorievich Fartushny, Sapernoe pole 28, kv. 15; Jury Nikolaevich Kakhovsky, pereulok Mechnikova, 3, kv. 1, all of Kiev; Vily Arsentievich Boiko, ul. Kirova, 104/6, kv. 1, Sumy; Zinovy Abramovich Sidlin, ul. vavilova, 45, kv. 21, Moscow; Konstantin Andreevich Juschenko, Sapernoe pole, 28, kv. 30, Kiev, all of U.S.S.R.

[22] Filed: Oct. 12, 1972 [21] Appl. No.: 296,816

[30] Foreign Application Priority Data Feb. 3, 1972 U.S.S.R 1740244 Sept. 9, 1970 U.S.S.R 1473314 11] 3,835,289 1451 Sept. 10,1974

Primary Examiner-J. V. Truhe Assistant Examiner-G. R. Peterson Attorney, Agent, or Firm-Holman & Stern [57] ABSTRACT An electrode for arc welding, comprising a core based on iron with alloying additives of chromium, nickel and titanium, and a coating consisting of fluorite, rutile concentrate, iron powder, chromium and-mica. In addition to the above components, said coating also contains magnesite, ferrotitanium and ferroniobium that ensure high plasticity and resilience to the deposited metal, the latter thus being resistant to the formation of pores and hot cracks.

22 Claims, No Drawings 1 ELECTRODE FOR ARC WELDING BACKGROUND AND SUMMARY OF THE INVENTION Known in the art in this country is an electrode for welding high-alloy corrosion-proof steels, which comprises an alloyed core based on iron with alloy additives (in weight per cent) of chromium (23 to 40), nickel (l l to 20), and titanium (O to 1), and a coating including fluorite, rutile concentrate, iron powder, chromium, and mica in the following weight content (in fluorite 6 to rutile concentrate 8 to l2 iron powder 40 to 60 chromium 2 to 10 mica l to 2 The known electrode suffers from a number of disadvantages. For example, the presence of iron powder in its coating is conducive to a higher content of absorbed moisture in the latter and a greater tendency of the deposited metal to pore formation.

Also a limited amount of chromium (2 to 10 weight per cent) introduced as ferritiser into the coating contributes to depositing a single-phase austenite chromonickel metal highly sensitive to the formation of hot cracks.

As a result, the metal thus deposited possesses limited plasticity (8 and resilience (a 10 kg.m/cm at 20 C and a poor anti-corrosion characteristic, as the known electrode lacks stabilizing components ensuring a high corrosion resistance.

It is an object of the present invention to eliminate the abovementioned disadvantages.

The primary object of the present invention is to provide an electrode for the arc welding of high-alloy corrosion-resistant steels, such as will ensure, during welding, the deposition of a metal with high physical and mechanical properties, e.g., plasticity (8 and resilience (a 12 kgmlcm at 20 C, and resistant to the formation of pores and hot'cracks, unlike known electrodes of the same type.

A more particular object of the-invention is the provision of an electrode for the arc welding of high-alloy corrosion-proof steels, such as will ensure, in the course of welding, the production of a metal possessing high physicaland mechanical properties, e.g., plasticity (6 30%) and resilience (a 12 kgmlcm Another object of the invention is to provide an electrode, such as will ensure, in the course of welding, the production of a metal resistant to the formation of pores and hot cracks, i.e., possessing a high corrosion resistance. r p

The object of the present invention has beem accomplished by provision of an electrode for the arc welding of high-alloy corrosion-proof steels, consisting of a core based on iron with alloy additives (in weight per cent):

chromium 23 to 40, nickel 11 to 20, titanium 0 to l, and a coating including fluorite, rutile concentrate, iron powder, chromium, and mica, wherein, according to the invention, the coating also contains, in addition to the above components, magnesite, ferrotitanium and ferroniobium, the weight contents being as follows (in fluorite 5 to [2 rutile concentrate 8 to 25 iron powder 20 to 60 chromium l to 16 mica l to 6 magnesite 3 to 25 ferrotitanium 2 to 10 ferroniobium 0 5 to 10 When included as a component in the electrode coating, magnesite is conducive, thanks to its dissociation in welding, to reducing both the partial pressure of by drogen in the arc atmosphere and the tendency of the deposited metal to pore formation. Moreover, the efficiency of the arc energy balance tends to rise with the resultant increase in welding efficiency in general. Note should be made that a content of the introduced magnesite below 3% fails to help reduce the tendency to pore formation because the hydrogen partial pressure remains high. Its provision above 25% is not practical, as this sharply deteriorates the welding properties of the electrode (the arcing stability is affected).

Commonly known is the effect of ferrotitanium and ferroniobium as stabilizers of deposited metal. If introduced in combination, they ensure a more complete assimilation of niobium owing to the deoxidizing effect of ferrotitanium. Theintroduction of the latter below 2% fails to help ensure intensive transfer of niobium from the coating into the deposited metal, while a concentration above l0%-is not practical, as this results in burning out niobium instead of its assimilation. The introduction of ferroniobium into the coating below 0.5% fails to help ensure its content in the deposited metal (N /C l l required for a high corrosion resistance of the latter, whereas a concentration above 10% is not practical, as this does not result in further improving of the anti-corrosion characteristic of the deposited metal.

It is also known that ferrotitanium and ferroniobium, as ferritisers, are conducive to depositing austeniteferrite metal. When introduced into the electrode coating in the quantities mentioned above, these two elements together with magnesite contribute to depositing a metal with a good anti-corrosion characteristic and a reduced tendency to pore and hot crack formation, unlike known electrodes of the same type.

It is also expedient that the coating include, additionally, hematite, the weight content of the latterbeing 3 to 10%. l v

If introduced into the electrode coating, hematite is conducive to a stepped-up oxidation of hydrogen during welding and to the deposition of a metal resistant to the formation of pores of hydrogen origin. Equally, the plasticity and resilience of said metal increase not less than 30% thanks to the higher density of the latter. If introduced below 3%, hematite fails to ensure an oxidation of hydrogen, during welding, sufficient to deposit a pore-free metal. If introduced above 10%, hematite results in an intensive oxidation of ferritisers (chromium, titanium, and niobium) during welding and the likely deposition of a pure austenite metal susceptible to the formation of hot cracks, which is, of cours not practical.

It is also expedient that the coating include potassium carbonate (0.3 to 1 weight per cent).

The effect of potassium carbonate as arc plasticizer and stabilizer is well-known. If introduced in the above quantities (0.3 to 1 weight per cent), it contributes to a higherplasticity of the coating mass of the electrode and facilitates producing the latter. Moreover, the electrode thus produced boasts of a high burning stability. The introduction of potassium carbonate in an amount 0.3%fails to ensure an increasein the plasticity of the coating mass, while a concentration above 1.0 increases sputtering inwelding.

The authors have established that, the above properties of the deposited metal will best manifest themselves when an electrode with the following weight content is used (in fluorite to 12 rutile concentrate 8 to 25 iron powder 20 to 60 chromium l to 15 mica l to 6 .magnesite 3 to 9 ferrotitanium 5 to ferroniobium l to 8 hematite 4 to 8 potassium carbonate 0.3 to 0.6

The contents of fluorite, rutile concentrate and magnesite being respectively less than 5, 8, and 3 per cent, the welding properties of the electrode and the quality of the deposited metal become affected. Moreover, the coating power of slag'and its ability to peel off the deposited metal turn out aggravated. Besides, the gas and slag protection of the deposited metal also deteriorates and the latter thus contains excessive gases and, as a result, has low plastic and resilient properties. In case the weight contents of the above components are respectively higher than 12,25, and 9, the welding characteristics of the electrode are also affected; specifically, the

slag fluidity increases.

The content of hematite above 4% does not ensure effective suppression of porosity in welding and a content above 8% results in an excessive oxidation of chromium and niobium.

above is not expedient, as this results in depositing a double-phase metal with the content of the ferrite phase being above 10%, which results in the affected plasticity and resilience of the deposited metal, particularly manifest at low temperatures (-196 C).

The content of ferrotine and ferroniobium respectively below 5 andl (in weight percent) fails to ensure' the high corrosion resistance of the-depositedmetal, while a content above respectively-l0 and 8 assists in depositing a double-phase austenite metal with the ferrite base being above 10%, which cannot but reduce its plasticity and resilience, which is also well manifest at low temperatures (l.96C).

The introduction of mica and potassium carbonate below 1 and 0.3 (in weight per cent) respectively does not ensure the production of a plastic coating mass and impedes the manufacture of electrodes, while a content above 6 and 0.6 respectively increases the tendency of the deposited metal to pore formation, as mica contains crystallized moisture, whereas an increase in the content of potassium carbonate is not practical, as this does not increase further the plasticity of the electrode coating mass.

It is knownthat the presence of nickel in the coating of an electrode for the arc welding of high-alloy corrosion-proof steels contributes to the anti-corrosion characteristic of the deposited metal. Therefore'it is quite reasonable that, in addition to the above components, the electrode coating also include up to 10% weight per cent of nickel. Its introduction above this figure is not practical, as this may result in depositing a purely austenite metal susceptibel to the formation of hot cracks.

Furthermore, it has turned out highly practical that the electrode coating have the following composition (in weight per cent):

fluorite 5 to 12 rutile concentrate 8 to 20 iron powder 20 to 60 chromium 8 to 16 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to 1.0 nickel 2 to 8 The content of nickel below 2 weight per cent does not ensure a higher corrosion resistance for the deposited metal and a content above 8-weight per cent is not practical, as this results in depositing a purely austenite metal susceptible to the formation of hot cracks.

The introduction of nickel into the electrode coating is possible at the expense of any slag-forming component or iron powder but is most reasonable atthe expense of the latter, as this helps regulate the content of the ferrite phase in the deposited metal.

It is practical for depositing a metal with high physical and mechanical properties as well as a good anticorrosion characteristic that the electrode coating contain up to 30 weight per cent of chromonickel powder. If the content of the latter in the coating amounts to 30%, this contributes to depositing a metal with a high corrosion resistance, as the positive effect of these elements on this characteristic of the deposited high-alloy metal is well-known.

The content of the chromonickel powder above 30% is not practical, as this leads to deterioration of the welding characteristics of electrodes (their pressing treatment).

Furthermore, it has turned out that'the following weight content of the electrode coating is most expedient (in fluorite rutile concentrate .8 to 20 iron powder 20 to 40 chromium l to 8 mica l to.6

' magnesite 3 to 18 -Continued ferrotitanium 2 to lo ferroniobium 0.5 to hematite 3 to 10 potassium carbonate 0.3 to L0 chromonickel powder to 23 The chromonickel powder content below 15 weight per cent does not produce any substantial effect on the corrosion resistance of the deposited metal, while a content above 28 weight per cent is not practical, as the welding properties of the electrode (pressing ability) become deteriorated and the conditions of thermal treatment more complicated.

The introduction of chromonickel powder is expedient at the expense of chromium and iron powder, especially at the expense of the latter, because this helps deposit a metal with wide limits of alloying by chromium and nickel and, correspondingly, with a high corrosion resistance.

However, the total content of chromium in the coating must not exceed 15%, as this would result in depositing a metal with a high content of ferrite base, which deteriorates its plasticity and resilience, reduced resilience being especially felt at low temperatures (-196 C).

It is economically expedient that the electrode coating include up to 30 weight per cent of ferrochromium whose presence ensures high physical and mechanical properties (plasticity and resilience) as well as proper corrosion resistance.

The weight content of ferrochromium in the electrode coating up to 30 is conducive to depositing a metal with a good anti-corrosion characteristic. The

similar content above 30% is not practical, as this results in depositinga double-phase metal with the ferrite base content above 10%, which affects its plasticity and resilience, especially at low temperatures (-196 C). Finally, it is most practical that the coating elements have the following weight contents (in rutile concentrate iron powder chromium mica magnesite ferrotitanium ferroniobium hematite potassium carbonate ferrochromium The content of ferrochromium below 10 weight per cent does not ensure a higher corrosion resistance of the deposited metal, while a content above 26% is not practical, as this contributes to depositing a metal with the ferrite base constituting more than 10% and the resultant deterioration of its plasticity and resilience, which is especially manifest at low temperatures (l96 C).

The introduction of ferrochromium into the coating is most expedient at the expense of chromium and iron powder. This helps ensure high mechanical and physical properties (plasticity and resilience) plus a high corrosion resistance. Besides, the introduction of ferrochromium is economically justified, as it is cheaper.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Other details and advantages of the invention will be more apparent from the following description of its exemplary embodiments.

The main criterion in selecting the composition of electrode coatings was to deposit a metal with high plasticity (8 30%) and resilience (a,, l2 kgm/cm and resistant to the formation of pores and hot cracks.

Electrodes of such content have marked advantages over the known electrodes of the same type, which has been proved by experiments.

Experimental welding was done by electrodes consisting of a core with the following chemical composi' tion (in weight per cent): chromium 25.6, nickel 12.8, titanium 0.12, iron the remainder. The contents (in weight per cent) of electrodes are furnished in Table l.

Electrodes of the above compositions were used for the arc welding and multilayer deposition of samples 12 mm thick and made of a steel of the following weight content (in C 0.08; Si 0.6; Mn 1.45; Cr l8.2; Ni 9.6; S $0.02; and P 0.02. 4

Welding and depositing were done by means of DC. of reversed polarity in the lower position by electrodes 5 mm in dia. with a coating weight factor (C.W.F.) of

Welding conditions were as follows: r a, ars 28 V and weldtna 9 The results of testing the weld metal and the deposited metal are shown in Table 2.

Taking into account all that has been stated above, the test data and practical experience, it is possible to conclude that, unlike known electrodes of the similar type, the proposed electrodes ensure high mechanical and anticorrosion Table 2 Conventional Characteristics of weld metal and demsited metal symbols Critical Dia. and Loss 'of Relative Charpy reof rate of amount built-up extension silience electrodes strain of pores I metal in testing in tests at leading on 100 mm when boilat 200kgm/cm to crack of ed in 65% 20C, formation, weld HNO; for

' mm/min. 120 h,

- mm/year 1 22.6 1.2mm 0.6 3l.4-33.6/33.0 9.8-1 l.6/10.8 2 pcs ll 29.8 7 none 0.45 36.840.4/3 8.2 l2.8l4.l/l3.5

lll 29.8 none 0.42 37.240.0/3 8.5 13.6-15.4/139 IV I 29.8 none 0.38 42.043.5/42.8 l4.6-l7.4/15.8

v 29.8 none 0.40. 14.0-16.4/l5.l

characteristics of the deposited chromonickel metal, along with its resistance to pore and hot crack formation. The ferrite base in the deposited metal amounts to 3 to 12%.

In addition to depositing quality metal, the proposed electrodes ensure a high welding efficiency (40 to. 6O glmin, depending on electrode diameter). The novel istics easy inflammation of the are, easy peeling-off of the slag skin from the deposited metal and the weld, deepgrooves included. The welding process does not require operation by a top-class welder, as contact arc welding is possible. Also typical of the electrodes is minimal sputtering. The yield of deposited metal amounts to 150 to 180%.

Note can also be 'made that electrodes Il-IV differ from electrodes I by their higher resistance to pore and hot crackformation.

Electrodes Ill-IV have proved good in manufacturing and operating chemical equipment in conditions of the presence of nitrous acid and liquefied gases.

Naturally, those skilled in the art may introduce various alterations and modifications into the design of the proposed electrode which is not limited by terms adopted, without departing from the spirit and scope of the invention, however.-

What we claim is:

1. An electrode for the arc welding of high-alloy corrosion-proof steels, comprising a core based on iron with alloying additives in percent by weight: chromium 23 to 40. nickel 11 to 20, titanium to 1; plus a coating including elements whose weight contents are as follows in percent by weight:

fluorite to 12 rutile concentrate 8 to 25 iron powder m 60 chromium v l to 16 mica l to 6 magnesite 3 to ferrotitanium 2 to 10 ferroniobiurn 0.5 to 10 25 weight 0.3 to 1.0.

4. An electrode as'claimed in claim 2, wherein the coating contains potassium carbonate in percent by weight of 0.3 to 1.0.

5.,An electrode as claimed in claim 2, wherein the electrodes are'characterized by high welding charactercoatmg comams the following elements in Percent y weight:

rutile concentrate 3 5 iron powder chromium mica magnesite ferrotitanium ferroniobium hematite 40 potassium carbonate 5tol2 8to25 20to60 ltolS lto6 Sto l0 lto8 4to8 0.3 to 0.6

weight:

rutile concentrate iron powder chromium mica magnesite ferrotitanium ferroniobium hematite potassium carbonate 7. An electrode as claimed in claim 1, wherein the 5tol2 8to25 20to60 ltolS lto6 3to9 5tol0 1to8 4to8 0.3 to0.6

coating contains nickel in percent by weight of up to 8. An electrode as claimed in'clairn 2, wherein the coating contains nickel in percent by weight of up to 9. An electrode as claimed in claim3, wherein 'th'e coating contains nickel in percent by weight of up to 10. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:

fluorite 5 to 12 rutile concentrate 8 to 20 iron powder 20 to 60 chromium 8 to 16 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 3 to 1.0 nickel 2 to 8 11. An electrode as claimed in claim 6, wherein the coating contains the following elements in percent by weight:

fluorite 5 to l2 rutile concentrate 8 to 20 iron power 20 to 60 chromium 8 to 16 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to L0 nickel 2 to 8 fluorite 5 to 12 rutile concentrate 8 to 20 iron powder 20 to 40 chromium l to 8 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to l chromonickel powder to 28 16. An electrode as claimed in claim 3, wherein the coating contains the following elements in percent by weight:

fluorite 5 to 12 rutile concentrate 8 to 20 iron powder 20 to chromium l to 8 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to 1.0 chromonickel powder 15 to 28 17. An electrode as claimed in claim 1, wherein the coating contains ferrochromium in percent by weight of up to 30.

18. An electrode as claimed in claim 2, wherein the coating contains ferrochromium in percent by weight of up to 30.

19. An electrode as claimed in claim 3, wherein the coating contains ferrochromium in percent by weight of up to 30.

20. An electrode as claimed in claim 7, wherein the coating contains ferrochromium in percent by weight of up to 30.

21. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:

fluorite 5 to 12 rutile concentrate 8 to 20 iron powder 20 to 40 chromium l to 5 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to 1.0 ferrochromium 10 to 26 22. An electrode as claimed in claim 11, wherein the coating contains the following elements in percent by weight:

fluorite 5 to l2 rutile concentrate 8 to 20 iron powder 20 to 40 chromium l to 5 mica l to 6 magnesite 3 to 18 ferrotitanium 2 to 10 ferroniobium 0.5 to 10 hematite 3 to 10 potassium carbonate 0.3 to 1.0 ferrochromium 10 to 26 

2. An electrode as claimed in claim 1, wherein the coating contains hematite in percent by weight of 3 to
 10. 3. An electrode as claimed in claim 1, wherein the coating contains potassium carbonate in percent by weight 0.3 to 1.0.
 4. An electrode as claimed in claim 2, wherein the coating contains potassium carbonate in percent by weight of 0.3 to 1.0.
 5. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:
 6. An electrode as claimed in claim 3, wherein the coating contains the following elements in percent by weight:
 7. An electrode as claimed in claim 1, wherein the coating contains nickel in percent by weight of up to
 10. 8. An eleCtrode as claimed in claim 2, wherein the coating contains nickel in percent by weight of up to
 10. 9. An electrode as claimed in claim 3, wherein the coating contains nickel in percent by weight of up to
 10. 10. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:
 11. An electrode as claimed in claim 6, wherein the coating contains the following elements in percent by weight:
 12. An electrode as claimed in claim 1, wherein the coating contains chromonickel powder in percent by weight of up to
 30. 13. An electrode as claimed in claim 2, wherein the coating contains chromonickel powder in percent by weight of up to
 30. 14. An electrode as claimed in claim 3, wherein the coating contains chromonickel powder in percent by weight of up to
 30. 15. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:
 16. An electrode as claimed in claim 3, wherein the coating contains the following elements in percent by weight:
 17. An electrode as claimed in claim 1, wherein the coating contains ferrochromium in percent by weight of up to
 30. 18. An electrode as claimed in claim 2, wherein the coating contains ferrochromium in percent by weight of up to
 30. 19. An electrode as claimed in claim 3, wherein the coating contains ferrochromium in percent by weight of up to
 30. 20. An electrode as claimed in claim 7, wherein the coating contains ferrochromium in percent by weight of up to
 30. 21. An electrode as claimed in claim 2, wherein the coating contains the following elements in percent by weight:
 22. An electrode as claimed in claim 11, wherein the coating contains the following elements in percent by weight: 